The goals of this Program Project grant are to develop and validate molecular biomarkers reflective of exposure, effect and risk from environmental carcinogens and translate these biomarkers as endpoints for the design and implementation of preventive interventions in high risk populations. Several underlying public health-based beliefs provide credence for attainment of these goals including the understanding that there are subsets of high risk people within populations that are most susceptible to disease. This susceptibility may be a consequence of the dose of environmental carcinogens but also other inherent susceptibility factors, including genetic background, other host factors or concomitant environmental exposures. Thus, biomarkerbased methods that can identify high risk individuals with specificity and selectivity will greatly facilitate the implementation of a spectrum of targeted preventive interventions directed towards reducing disease incidence. In total, the impact of molecular biomarker research ranges from exposure assessment, risk assessment and management, to clinical and population-based prevention trials. This Program consists of 3 research Projects; Development and Evaluation of Exposure Biomarkers: PAHs (polycyclic aromatic hydrocarbons), PhIP (2-amino-1-methyl-6-phenylimidazo[4,5-b]- pyridine), and Aromatic Amines; Validation and Application of Risk Biomarkers In Human Studies; and Use of Biomarkers In Human Interventions. The environmental carcinogens that are being studied are present generally in the environment and frequently in the diet and include aflatoxin, heterocyclic amines, aromatic amines and polycyclic aromatic hydrocarbons. Underpinning the research in these Program areas are Core facilities with expertise in Analytical Chemistry and Biostatistics and Epidemiology.